Abstract
Core-shell-corona type triblock copolymer poly(styrene-b-2-vinylpyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) micelles have been selected here to direct the synthesis of mesoporous Pt-on-Pd spheres, consisting of a Pd concentrated core and a Pt shell, as established by elemental mapping. It is important to note that the size of the PS core determines the resultant size of the mesopores. A self-evaporation method has been developed to prepare swollen micelles, so as to further enlarge the pore size (similar to 40 nm). Compared with commercially available catalysts (e.g., Pt black or Pt, 20 wt% on carbon black), good oxygen reduction reaction performance on the mesoporous Pt-on-Pd spheres is observed, due to the exposure of the most active Pt (111) planes and the synergistic effects from Pt and Pd in the pseudo core-shell structure.